Pregnancy Due Date Calculator
Enter the first day of your last menstrual period (LMP) to instantly see your estimated due date, gestational age, trimester, and estimated conception date.
Your estimated due date (EDD) is calculated using Naegele's rule — the same method used by OB-GYNs and midwives worldwide: add 280 days (40 weeks) to the first day of your last menstrual period. This calculator also adjusts for cycle lengths other than 28 days and tells you your current gestational age and trimester.
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Last reviewed: April 2026Report an error
Estimated Due Date
December 14, 2026
Your estimated due date is December 14, 2026. You are currently 6 weeks and 0 days pregnant (Trimester 1). 238 days remaining.
Gestational Age
6w 0d
Trimester
1st Trimester
Days Remaining
238 days
Est. Conception
March 23, 2026
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How to Use This Due Date Calculator
- Enter the date of the first day of your last menstrual period (LMP).
- Adjust cycle length if it differs from 28 days.
- Read your estimated due date (EDD) — this is 40 weeks from LMP.
- See your current gestational age in weeks and days.
- Confirm or refine with an ultrasound (first trimester ultrasound is most accurate).
Frequently Asked Questions
- Using Naegele's rule: take the first day of your last menstrual period, add 1 year, subtract 3 months, and add 7 days — which equals LMP + 280 days. If your cycle is longer or shorter than 28 days, the formula is adjusted proportionally.
- Only about 5% of babies are born on their exact due date. Most are born within ±2 weeks. A first-trimester ultrasound is more accurate than LMP alone, especially if your cycles are irregular.
- Gestational age counts from the first day of your LMP — not from conception. So at "4 weeks pregnant," you conceived approximately 2 weeks earlier. This is standard medical convention.
- First trimester: weeks 1–13. Second trimester: weeks 14–27. Third trimester: weeks 28–40. This calculator uses these standard boundaries.
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